Apparatus for reducing the operating noise of a chain saw

ABSTRACT

Apparatus for reducing the noise level of an operating chain saw characterized by synergistically interacting exhaust conduit means, surge chamber means, and acoustic filter means, possibly associated with arcuate deflector means or flexible reed, sound attenuating means.

United States Patent 1191 Bailey 1 1 APPARATUS FOR REDUCING THE OPERATING NOISE OF A CHAIN SAW [75] Inventor: Jay Richard Bailey, Woodland Hills,

Calif.

[73] Assignee: McCulloch Corporation, Los

Angeles, Calif.

[22] Filed: Jan. 25 1972 [21] Appl. No.: 220,632

[52] U.S. Cl. 30/383, 181/40 [51] Int. Cl. B27b 17/02, F01m 1/02 [58] Field of Search 30/383387;

[5 6] References Cited UNITED STATES PATENTS 5/1972 Tenney 181/40 X 1451 Mar. 26, 1974 3,168,936 2/1965 Gordon 181/40 3,106,985 10/1963 Recupito 181/36 R 3,404,749 10/1968 Miller et a1. 181/40 3,643,759 2/1972 Bailey 181/36 R FOREIGN PATENTS OR APPLICATIONS 682,862 3/1964 Canada 181/40 Primary ExaminerDonald R. Schran Attorney, Agent, or Firm-Burns, Doane, Swecker & Mathis [57] ABSTRACT Apparatus for reducing the noise level of an operating chain saw characterized by synergistically interacting exhaust conduit means, surge chamber means, and acoustic filter means, possibly associated with arcuate deflector means or flexible reed, sound attenuating means.

7 Claims, 13 Drawing Figures SHEEY 3 BF 4 PATENTED HARZB I974 APPARATUS FOR REDUCING TIIE OPERATING NOISE OF A CHAIN SAW GENERAL BACKGROUND, OBJECTS, AND SUMMARY OF INVENTION As a result of concerted efforts directed toward the improvement of environmental conditions, practitioners in the chain saw art have been concerned with the reduction in operating noise of chain saw mechanisms.

Because the bulk of chain saws in use today are operated by small two-cycle engines (including piston and cylinder assemblies with a piston driven by a crankshaft), chain saw designers are constantly faced with a design dilemma.

This design dilemma results from the fact that a noise level reduction is highly desirable but a noise level reduction effected through the use of a muffler is usually accompanied by a reduction in power output of the engine employed to drive the chain saw. Since the driving engine is often relatively small in the first instance, due to the desire to maintain chain saw weight at 30w level, the amount of power which can be sacrificed for noise reduction purposes is small.

This margin of power which can be sacrificed for noise reduction purposes is sufficiently marginal that chain saw muffler design presents extraordinary complexities.

These complexities are of such a magnitude that the chain saw muffler art entails a certain degree of imponderables or unpredictable factors.

While those practicing in this art avail themselves of their substantial skill and background in providing de-' signs which are believed to have a significant potential, many muffler designs prove to be inadequate and good results may unexpectedly result from particular, synergistically interacting, combinations of muffler components.

So it is that, in the present invention, significantly im proved results have been obtained with structural combinations where the overall effects of the improved results would not have been readily and completely predictable in light of the individual components of these muffler structures or their particular modes of combination.

Indeed, viewing the art in retrospect in light of prior patent art, including: U.S. Pat. Nos., 1,487,312, Hull; 1,953,264, Rouen et al.; 2,732,026,. Potts; 2,975,854, Bakke et al.; 2,126,979, Max; 3,l68,936, Gordon; 3,200,902, Jones; 3,378,099, Gordon; it is not believed that the overall beneficial results obtained through the present invention would have been anticipatable.

However, to the extent that the present invention involves an incorporation of inventive concepts featured in my priorapplication Ser. No. 101,572, filed Dec. 28, 1970, entitled Muffler with Reed Valve Providing Continuous Venting/{and assigned tothe assignee of the present invention, and my prior US. Pat. No. 3,318,412, .at least a significant level of operating improvement would have been foreseen.

A particular object of the invention is to provide a simplified chain ,saw'muffler structure which operates to reduce the operating noise of a chain saw engine to an acceptable degree while maintaining an unusual extent of operational ruggedness and unusually long-operating life for components.

It is a further object of this invention to provide such an improved muffler structure including a spark arrestor mechanism which, if partially disintegrated over a prolonged operating life, will tend to be selfremoving from the muffler interior rather than tending to become lodged in the muffler interior.

It is a further object of the invention to provide such an improved chain saw muffler which may be directly mounted on the exterior of a chain saw engine cylinder in direct metal-to-rnetal contact therewith so as to avoid the loosening problems associated with muffler mountings requiring a gasket-type installation.

It is a still further object of this invention to provide such an improved chain saw muffler which is believed to have an operating life which is in excess of several hundred hours and well in excess of the operating life of certain mufflers replaced by a muffler of the present invention and heretofore used in connection with chain saw operations.

It is a further object of the present invention to provide an improved,.ruggedized chain saw muffler which is devoid of certain prior artmuffler problems, including a tendency of internal baffle mechanisms to break One apparatus aspect of the invention intended to accomplish at least certain of the foregoing objectives entails an apparatus including conduit means, surge chamber means, and acoustic filter means in a unique combination. I I

In this particular apparatus aspect of the invention, the conduit means is operable to transmit exhaust fluid from the piston means of a piston and cylinder means engine assembly. Thesurge chamber means is operable to receive exhaust fluid from this conduit means and is operable to be supported on the exterior of the cylinder means. I

The acoustic filter means of this combination includes first, generally perforate, outlet passage defining means. A generally longitudinal axis of this first outlet passage defining means is transversely displaced from a generally longitudinal axis of the conduit means such that the conduit means and first outlet passage defining means are mutually transversely offset. A second generally perforate outlet passage defining means is contained within the first outlet passage defining means and is at least partially spaced therefrom.

First end portions of each of the first and second outlet passage defining means are housed within the interior of the surge chamber means and closed by barrier means. A perforate wall means extends generally transversely of and between second end portions of the first and second outlet passage defining means.

The outlet means and perforate wall means are operable to transmit exhaust fluid to the exterior of the surge chamber means. g

In this acoustic filter means combination, the first outlet passage defining means includes a plurality of first perforation means, while the second outlet passage means includes a a plurality of second perforation means. The plurality of second perforation means are operable to arrest the passage of sparks carried by exhaust fluid transmitted to the interior of the surge chamber means from the conduit means.

Each of the first perforation means of the first outlet passage defining means generally encircles, and exposes to the interior of the surge chamber means, a plurality of second perforation means of the second outlet passage defining means.

A constricted flow path means is interposed generally between the first and second outlet passage defining means.

The aforesaid combination also includes deflector means operable to deflect exhaust fluid exiting from the outlet means of the second outlet passage defining means.

Another apparatus aspect of the invention, to be employed in the context of reducing the noise generated by a piston and cylinder type engine mechanism including a crankshaft, is characterized by a unique combination of conduit means, surge chamber means, acoustic filter means, and cantilever beam means.

In this combination the conduit means and surge chamber possess characteristics of the type heretofore noted.

The acoustic filter means includes generally perforate outlet passage defining means, with this outlet passage defining means being transversely offset from the conduit means. A barrier means within the surge chamber means closes a first end portion of the outlet passage defining means. An outlet means is provided by a second end of the outlet passage defining means for transmitting exhaust fluid to the exterior of the surge chamber means. A plurality of spaced perforation means is included in the outlet passage defining means.

The cantilever beam means of this combination extends generally transversely across the outlet means of this outlet passage defining means and includes flexible reed means. A cantilever support anchor means fixedly secures one end of this reed means to the exterior of the surge chamber means, with another end of the reed means extending at least partially across the outlet means and movable generally outwardly thereof.

A third independently significant apparatus aspect of the invention, also employed in the context of an engine assembly as heretofore noted, includes a combination of conduit means, surge chamber means, acoustic filter means, and tubular baffle means.

In this third aspect of the invention the conduit means, surge chamber means and acoustic filter means are characterized by features as described in connection with the second aspect of the invention. In this particular combination aspect, the tubular baffle means comprises a plurality of tubular baffles located within the interior of the surge chamber means. These tubular means functionas housings for fastening means which serve to secure the surge chamber means to the exterio'r of a cylinder of an engine, the noise output of which is to be reduced. These tubular means are mutually displaced and disposed nonsymmetrically in relation to the outlet passage defining means of the acoustic filter means. I

Optimum advantages of the invention are derived where each of the foregoing combinations is employed in the context of a two-cycle engine operated chain saw.

Particular optimization may be attributable to specific aspects of the invention entailing specific configurations of the conduit means, surge chamber means and acoustic filter means and specific orientations of these components relative to vibration generating directions of a chain saw.

DRAWINGS Without implying limitation as to the scope of the invention, certain significant aspects of the invention will be described with reference to preferred embodiments shown in the appended drawings.

In the Drawings:

FIG. 1 provides a perspective, fragmentary view of an exemplary chain saw with which the present muffler invention may be advantageously practiced;

FIG. 2 provides, in exploded format", a perspective view of components of one preferred muffler embodiment which may be incorporated in the FIG. 1 chain saw;

FIG. 3 provides a front side elevational view of the assembled FIG. 2 muffler;

FIG. 4 provides a vertical elevational view of the FIG. 3 muffler, viewed from the rear side of the muffler which is ordinarily mounted in direct metal-to-metal contact with the exterior of the cylinder of the FIG. 1 chain saw engine, with the muffler view of FIG. 4 being partially broken away to reveal certain internal details;

FIG. 5 provides a transverse sectional view of the FIG. 3 muffler as viewed along section line 5-5 of FIG. 3;

FIG. 6 provides another transverse sectional view of the FIG. 3 muffler as viewed along section line 66 of FIG. 4;

FIG. 7 provides an enlarged, exploded format view of housing components of the FIG, 3 muffler, illustrating the manner in which these components may be assembled for brazing purposes;

FIG. 8 provides an enlarged sectional view of the interior of an acoustic filter mechanism included in the FIG. 3 muffler as viewed generally along section line 88 of FIG. 3;

FIG. 9 provides, in exploded format, a perspective view of an alternate preferred embodiment of a deflector mechanism according to the invention;

FIG. 10 provides an enlarged, fragmentary, vertically sectioned view of a second muffler embodiment in accordance with the present invention as depicted in FIG. 9 and comprising a modification of the FIG. 3 muffler which permits a deflector mechanism to be rotatably adjusted about the longitudinal axis of an acoustic filter means;

FIG. 1 1 provides an enlarged sectional view of a third modification of the FIG. 3 muffler, viewed generally along the location of section line 88 of FIG. 3, and illustrating the installation of a cantilever beam, noise attenuating device in combination with a continuous venting system;

FIG. 12 provides, in exploded format a perspective view of components of the FIG. 11 cantilever beam assemblies; and

FIG. 13 provides an end elevation view of the FIG.

modification and a cantilever beam means and continuous venting arrangement.

DETAILED DESCRIPTION OF PRINCIPAL EMBODIMENTS FIG. 1 illustrates a representative chain saw 1, including a muffler 1 fabricated in accordance with any of several embodiments of the present invention.

Chain saw 1 includes a guide bar 101. A cutter chain 102 is slidably supported on the periphery of the guide bar 101 for movement'through a cutting plane. This cutting plane may be considered to comprise a longitudinally extending, upright median plane coextensive with the generally ovate cutter chain configuration.

Chain saw 1 comprises an engine assembly 103 including a piston and cylinder means 104. As shown in FIG. 1, a cylinder component 105 of the piston and cylinder assembly 104 may be oriented so that the 'axis of reciprocation of the piston contained within the cylinder 105 extends generally longitudinally of the guide bar 101 and the aforesaid cutting plane.

A crankshaft means 106, including the external housing 107 shown in FIG. 1, is operated in a manner now well understood to translate reciprocating movement of the piston of the engine assembly 103 into rotary movement of a sprocket wheel which is disposed in driving engagement with a cutter chain 102.

This crankshaft is mounted for rotation about an axis of crankshaft rotation 108 which extends generally perpendicular to the aforesaid cutting plane, i.e., a planar extension of the longitudinal'upright median plane of the guide bar 101.

Wlth this arrangement, the chain saw 1 will generate vibrations principally aligned with a plane extending generally parallel to or longitudinally of the aforesaid cutting plane. As a consequence, the axis of crankshaft rotation 108 may be deemed to pass generally perpendicular to this principal vibration plane.

' In describing the various preferred embodiments of the muffler 2, reference will be made to a first embodiment illustrated in FIGS. 28, to a second embodiment illustrated in FIGS. 9 and 10, and a third embodiment illustrated in FIGS. 11-13.

FIRST EMBODIMENT WITH DUAL CYLINDER ACOUSTIC FILTER AND DEFLECTOR The first embodiment of muffler 2 shown in FIGS. 2 -8 comprises a conduit means 3 which is operable to transmit exhaust fluid from the cylinder means 105.

As is shown generally in FIGS. 1, 5 and 6, conduit means 3 is disposed in direct metaI-to-metal engagement with an exterior mounting boss 109 of the cylinder 105 and communicates directly with a cylinder ex-- haust port 110. This metal-to-metal juncture 111 may be supplemented by a gasket 1110 as shown in FIG. 5 but the metallic extremity ofthe conduit 3 is disposed largely in direct, contiguous, abutting engagement with section extending transversely of axis 301. Conduit 3 may be somewhat composite in nature, comprising a sheet metal portion 303 connected (as by brazing) with an apertured, plate-like terminus 304. The terminus 304, being plate-like and flat in configuration, will ensure contiguous, uniform and generally flush engagement between the end of the conduit 3 and the boss 109 at the juncture zone 111.

In certain instances, conduit means 3 may not be elongate as shown in FIGS. 2-6 and instead may merely comprise a port or passage means in the base of surge chamber 4. Such an arrangement could result by fabricatingthe cylinder bosses 109 and 112 so that they were generally coplanar and engageable with spaced portions of a flat boss of a muffler unit.

Muffler 2 additionally includes a surge chamber 4. This surge chamber, as shown in FIG. 6, is operable to receive exhaust fluid from the conduit means 3 at a juncture zone 401 between these components.

The surge chamber 4 may be fabricated from metallic halves 402 and 403 whichare telescoped together and brazed or crimped at juncture zone 404.

Body or shell portion 403 of the surge chamber means may be provided with a mounting pad zone 405 which is disposed in direce metal-to-metal engagement with a mounting boss 112 formed on the exterior of cylinder 105. In this manner, the surge chamber means 4 is supported directly on the exterior of the cylinder means 105.

As will be also understood from reference to FIG. 6, the conduit means 3 extends between the interior of the surge chamber means 4 to the juncture zone 111.

The surge chamber 4 has an overall, generally rectangular configuration (albeit somewhat rounded) encircling the surge chamber interior 406 and includes a generally rectangular cross section extending generally parallel with the aforesaid principal vibration plane.

Muffler 2 further includes acoustic filter means 5 depicted generally in FIGS. 5, 6 and 8.

Acoustic filter means 5 comprises a first, generally perforate, sheet metal cylinder means 501 having a longitudinal axis extending generally parallel to the axisof crankshaft rotation 108. A longitudinal central axis 502 of the first cylinder means 501 is transversely displaced from the longitudinal central axis 301 of the conduit means 3. Thus, the perforate cylinder means 501 and the conduit means 3 may be considered as being mutually transversely offset along a plane extending parallel to the aforesaid principal vibration plane.

Acoustic filter means 5 additionally includes a second, generally perforate, stainless steel, cylinder means 503 which is contained within the first cylinder means 501. This second cylinder means 503, at least when installed, is slightly smaller in diameter than the internal size 'of cylinder means 501 so as to be at least partially and generally radially spaced inwardly thereof.

A cap-like, end wall or barrier 504 serves to close first end portions 505 and 506 of cylinder means 501 and 503, respectively. As shown in FIG. 8, this metallic barrier cap 504 may be partially telescoped within a first inner end 505 of cylinder 501 and brazed into a fixed position relative to, and connected with, cylinder 501 as shown in FIG. 8.

Cap 504 provides an edge or annular ledge means 507 over which a first end 506 of the cylinder means 503 is partially telescoped, as generally shown in FIG. 8.

Thus, cap 504 comprises a barrier means which operates to close the first end portions 505 and 506 of the cylinder means 501 and 503. As will be further recognized, these first cylinder end portions 505 and 506 may be viewed as being generally mutually contiguous with the rim of cap 504 and housed within the interior of 406 of the surge chamber means 4.

The second or outer end 508 of cylinder 50] is deflected generally radially outwardly so as to provide a mounting ledge 508a. This ledge or rim is abuttingly engageable with an annular mounting shoulder 407 of the surge chamber means. Similarly, an outwardly deflected and generally radially extending shoulder 509 of the cylinder means 503 provides a mounting shoulder or rim disposed axially outwardly of but in engagement with, the rounded inner corner of shoulder 508a of the first cylinder means 501.

This arrangement permits the cylinder means 501, including its closure or cap 504, to be telescoped through a surge chamber opening 408, provided by shoulder 407, until shoulder 508a is disposed in abutting engagement with shoulder 407. Either before or after this assembly takes place, the inner cylinder 503 may be inserted into the position shown in FlG. 8, axially overlaps and peripherally engages the annular edge 507 of cap 504, with the outer or second cylinder end 509 generally resting on the shoulder 508a. With this arrangement, the radial thickness of cap edge 507 tends to regulate or define the radial spacing of cylinder means 501 and 503.

With this arrangement, the perforate, rim defining, upper end 509 of the inner cylinder 503 comprises perforate wall means extending generally transversely of and between the second or outer end portions of the first and second cylinder means 501 and 503. In addition, the upper end 509 of the cylinder 503, like the end 508 of cylinder 501, generally encircles the outlet means 510 which is operable to transmit exhaust fluid to the exterior of the surge chamber means.

The flow of this exhaust fluid to the interior passage 511 of the composite cylinder means 501-503 is facilitated by perforate side wall portions of the cylinder means 501 and 503.

Thus, as shown in FIGS. and 8, the outer cylinder 501 includes a plurality of generally radially extending, longitudinally elongate, and circumferentially spaced first perforations 512. As shown in FIGS. 5 and 8, two such longitudinally displaced rows of perforations 512 may be provided.

The inner cylinder 503 includes a plurality of generally radially opening and circumferentially and longitudinally spaced perforations 513. These perforations 513 may be fabricated as a longitudinally and circumferentially uniform perforation pattern.

It is contemplated that the openings 513 may be generally circular in cross section and that these openings would be of such a size as to arrest the passage of sparks which may be transmitted with exhaust fluid passing from space 406 into space 511.

Each of the perforations 512 is substantially larger than each perforation 513. Thus, each first perforation means 512 encircles, and generally exposes to interior space 406, a plurality of perforations 513. In this connection, it is contemplated that where the diameter of the perforations is on the order of 0.023 inches, the width of each opening 512 may be on the order of 0.125 inches, with the length of each such opening 512 being on the order of 0.50 inches.

The slight radial gap between the cylinders 501 and 503 provides a constricted annular flow path 514 extending longitudinally of and interposed generally radially between the first and second cylinder means 501 and 503. This flow path, having a radial width on the order of about 0.03 to 0.04 inches, and which is believed to perform a significant sound attenuating function, includes a generally imperforate, outer end wall portion 515 of the cylinder means 501.

The constricted annular flow path 514 extends generally along the axis 502. In this connection, it will be recalled that axis 502 extends generally perpendicular to the aforesaid principal vibration plane.

it will be noted at this point that the cutter chain 102 and the engine 103 are operable to generate vibrations generally aligned with this principal vibration plane and acting on the first and second cylinder means 501-503. These vibrations are generated so as to be directed generally transversely of the constricted annular flow path 514 and in general alignment with the cutting plane.

Before discussing additional elements of the muffler 2, it is worth noting that the flow of exhaust fluid between surge chamber interior 406 and acoustic filter interior 511 may be somewhat multidirectional in character.

Some of this fluid will flow generally radially between interior space 406 and space 51 1, while some fluid flow will be resisted by the solid wall portions of cylinder 503 so as to flow generally longitudinally of axis 502 along the path 514. Fluid flowing along the path 514 and adjacent theimperforate outer wall 515, if not discharged into interior 511 by the time it reaches the end ofthe cylinder assembly, may flow into the exhaust outlet 510 through the perforate end 509 of the inner cylinder 503.

Muffler 2 additionally includes a plurality of generally tubular components 6 which function primarily as housings for fastening members. However, these components 6 may also provide a from of internal baffle action in the surge chamber 4. These tubular components 6 also serve the function of reducing the unsupported or unbraced wall or panel area of the muffler chamber 4 and may act to reduce airborne noise eminating from vibrating wall or panel areas.

Thus, as shown in FIGS. 2-6, muffler 2 may include three generally tubular housing or baffle members 601, 602 and 603.

Each such baffle member extends generally parallel to the axis of crankshaft rotation and thus parallel to the axes 502 and 301.

As shown in FIG. 5, each such tubular housing or baffle member 601 may be brazed to surge chamber shell portion 402 at a juncture 604 and extend through the surge chamber interior 406.

Two of the baffles 601 and 602 may pass longitudinally through upper and lower ends of the conduit means 3, as generally shown in FIG. 5.

The inner ends of these baffle or housing members 601-603, i.e., the ends disposed adjacent the cylinder 105, may be secured by a brazing arrangement involving a telescoping assembly of components, generally shown in FIG. 7.

Thus, as shown in FIG. 7, a representative tubular member 602 telescopingly receives a generally tubular and radially flanged fitting 605. Another end of fitting 605 passes through an apertured portion of end wall lip 305 of conduit means 3 so as to be telescopingly received within an aperture 306 of mounting plate 304. With these components telescopingly assembled in this manner, as shown generally in FIG. 5, the brazing of fitting 605 to an end of tubular member 602 and to the base plate 304 will serve to effectively interconnect the components 602, 303 and 304.

The arrangement described in connection with member 602 is duplicated with respect to member 601.

This same general mode of assembly may be employed in connection with tubular member 603. This member may be secured by brazing to mounting pad portion 405 of shell 403. In this case, opposite ends of a tubular flanged fitment 606 may be partially telescopingly received within an end of tubular member 603 and an opening in wall 405, respectively, and be brazed to these components so as to effect their interconnectron.

. With respect to thegeneral orientation of components heretofore described, it is of significance to note that the conduit means 3, the first and second cylinder means 501 and 503, the constricted annular flow path 514, and the tubular baffle means 601-603are allarranged so that their longitudinal axes are generally mutually parallel. All of these components are subject to vibrations generated in general alignment with the principal vibration plane heretofore described.

The precise baffle phenomena which may be attributable to the baffle means 601-603 is not fully understood. Nevertheless, it .is believed that the nonsymmetric disposition of these baffle means, spaced generally radially outwardly of the cylinder means 501, contributes to a baffling action in the interior 406 of the surge chamber means 4.

' Muffler 2 may also include an arcuate deflector means 7 depicted generally in FIGS. 2-4 and 8.

Deflector means 7 is operable to deflect exhaust fluid exiting from outlet means 510 in a direction extending generally transversely of the axis of crankshaft rotation, albeit displaced from this axis.

Thus, deflector means 7 may include arcuate wall means 701 having a generally quarter-sphere configuration.

'This quarter-sphere configuration is oriented such that its center of curvature 702 is generally coincident with the central longitudinal axis 502 common to the first and second cylinder means 501 and 503, respectively.

The manner in which the deflector means 7 is installed will be appreciated by reference to FIGS. 2-4 and 8.

Thus, as there shown, quarter-sphere wall 701 may besupported on amounting rim 703 which has apertured clamp or ear means 704 and 705. A mounting plate 706 having a central aperture 707 generally coincident with constricted passage 514 may be provided. This mounting plate 706 may also include apertured ear portions 708 and 709.

I With the cylinder assemblies 501 and 503 positioned as shown in FIG. 8, the rim 703 and plate 706 may be positioned so as to dispose the apertured ear portions 704, 705, 708 and 709 in general alignment with threaded fastener receiving openings 710 and 711 formed on surge chamber means 4. The insertion of threaded fasteners 712 and 713 through these ear por tions and fastener receiving openings into threaded cooperation with threaded nut means 714 and 715 (brazed to the interior of surge chamber 4 in the form of a unitary arcuate plate as shown in FIG. 1) will complete the installation of the deflector assembly.

This completion of the deflector installation will concurrently serve to secure the cylinder means 501.and 503 in position. This will result due to a generally abutting engagement between the rim 706 and the cylinder flanges 508 and 509, as shown in FIG. 8. In this assembled position opening 707 will be coaxially alinged with, and generally coextensive with, outlet 510.

The position of the threaded fasteners 712 and 713 and their associated threaded nut means 714 and 715 may be such, as shown generally in FIGS. 1 and 8, as to cause the deflector wall 701 to be disposed with its opening 716 directed directly downwardly, i.e., away from the upper part of the chain saw where an operators hands would be disposed.

In certain instances, the deflector may be inverted and the wall means 701 configured so as to provide a deflected flow of exhaust fluid onto an operator's hands for operator hand warming purposes.

The deflector 701 may also be oriented so as to deflect warm exhaust fluid into portions of the chain saw for the purpose or warming components such as the carburetor, air filter, etc. located generally in upper area 113 of the chain saw shown in FIG. 1.

While the general manner in which the muffler 2 is mounted on the exterior of cylinder 103 has been described, some further attention to this mounting technique is now in order.

Thus, asshown in FIGS. 5 and 6, it will be noted that the braze connected fitments 605 and 606 provide shoulders or ledges 607. These ledges or shoulders may serve to abuttingly engage the heads 608 of threaded mounting screws 609 which pass through the fltments 605 and 606 into cylinder bosses 109 and 112, respectively.

With the muffler 2 thus installed, it will function to effectively attenuate noise generated by the engine means 103 through the synergistically cooperating interaction of the conduit means 3, surge chamber means 4, acoustic filter means 5, possibly facilitated by baffle action provided by baffle means 6.

In other words, exhaust fluid will flow from the cylinder discharge port 110 into the surge chamber interior 406. Baffling of this flow will result because of the displacement of the conduit means 3 and the cylinder means 501 and 503, and possibly also because of the nonsymmetric orientation and presence of the baffle means 601-603.

The thus baffled flow of fluid in the surge chamber will pass through the perforation means 512 and 513 into the interior space 511 for trasmittal to the exhaust outlet 510. I

Some. sound attenuation will probably result from passage of exhaust fluid through filter means 512. However, particular effective attenuation of sound is believed to be attributable to the sound attenuating influence of exhaust flow at least partially along the constricted passage 514, Le, between the cylinder means 501 and 503.

Exhaust fluid exiting from outlet 510 will be baffled by arcuate baffle means 7 so as to be deflected in the desired direction in relation to the chain saw and operator. This deflection may also function to provide a form of wall or barrier between the-exiting gas flow and the operator so as to further reduce the apparent sound level. Such a location of the deflector is illustrated in FIG. 1.

With the principal structure and operating characteristics of the FIG. 28 embodiment having been described, it is appropriate to now consider the second embodiment shown in FIGS. 9 and 10.

SECOND EMBODIMENT WITH ROTATABLE DEFLECTOR MEANS FIGS. 9 and 10 illustrate a second embodiment of the invention where the muffler 2 is provided with a rotatable or selectively adjustable deflector mechanism.

As shown in FIG. 9, deflector mechanism comprises a deflector assembly 717 which includes an annular rim 718. A quarter-sphere, deflector wall segment 719, like wall 701, projecting outwardly of passage 511, is supported by rim 718. The axis of curvature of quartersphere, wall segment 719 may be substantially or generally coincident with axis of curvature 502 of the passage 511.

As will be apparent from reference to FIGS. 9 and 10, deflector unit 717 is fsandwiched against mounting ring 706 in much the same manner that the deflector unit 701-703 is sandwiched against the ring 706, as described in connection with the FIG. 2 arrangement.

However, in this instance, the deflector assembly rim 718 is not intersected by the threaded fastener means 712 and 713.

Instead, the threaded fasteners 712 and 713 pass through mounting lugs 720 and 721. These lugs serve to journal the deflector assembly 717 on the exterior of surge chamber means 4 for rotation generally about the axis 502.

This journaling action is facilitated by arcuate, concave edges 722 and 723 of mounting flanges 720 and 721, respectively. These arcuate edges 722 and 723 generally peripherally engage or confine an annular, axially extending lip portion 724 of unit 717. This lip portion is carried by the generally radially extending, flat rim portion 718 of assembly 717 as shown in FIG. 9 and merges into and comprises a portion of wall 719.

The-curved nature of recesses 722 and 723 cooperate to provide a rotary retainer engaging rim 724 so as to permit rotation of the assembly 717, while concurrently preventing displacement of the assembly 717 from journalled cooperation with the flanges 720 and .lnstead of employing separate flanges 720 and 721, these units may be interconnected by an annular, flat ring means which would be coextensive with the portions of flanges 720 and 721 bearing the recesses 722 and 723. In other words, a retainer ring much like element 706 may be employed to overlie rim 718, except that such a retainer ring would desirably be provided with spacer means much like spacer means 720a and 721a shown in FIG. 10, engageable with the exterior of the muffler body, and operable to position the retainer so as to provide a recess between the retainer and ring means 706 operable to receive rim 718.

With the journal arrangement above described, as permitted by the mounting flanges 720 and 721 or other mounting means and the passage of the fasteners 712 and 713 radially outside of the rim 718, a simple but effective rotatable deflector arrangement is pro- 'vided. This arrangement permits the orientation of quarter-sphere deflector walls 719 to be selectively and rotatably adjusted about the axis 502. It is contemplated that the loosening of screws 712 and 713 would permit such rotational adjustment and that the tightening of these screws would secure the deflector in a desired position.

Thus, in certain instances the deflector-wall may be oriented as shown in FIGS. 1 and 9 such that exhaust gas issuing from the outlet 510 will be deflected generally downwardly, away from the upper portion of the chain saw, i.e., the portion engaged and gripped by operator-hands. I

With the deflector opening 719a directed downwardly as shown in FIG. 10, or with the opening 716 directed downwardly as shown in FIGS. 1 and 8, the exhaust flow exiting from the outlet will be directed downwardly, in relation to an upright chain saw position, in a somewhat half-conical pattern, diverging outwardly from the vertical longitudinal median plane of the saw at an angle believed to be on the order of about 45". This rapidly spreading, conically shaped exhaust flow will be directed away from the operator during both bucking and felling" operations. As a result of the conical outflow, the exhaust gas will cool rapidly, allowing the surrounding air'to mix quickly with and cool the exhaust gas and thus reduce the hazzard of fire.

In other instances, it may be desirable to orient the deflector 719 such that it directs exhaust gas upwardly, possibly toward an operator hand for warming purposes.

It may also be desirable to orient deflector 719 so that it directs exhaust gas toward other portions of the chain saw for the purpose of flowing relatively warm air against chain saw components .for component warming purposes.

Various conduit configurations might be arranged in combination with deflector means 7 for permitting exhaust fluid to be redirected into the interior of the chain saw, probably for the purpose of preventing carburetor icing, by heating air flowing to a carburetor, and/or to a carburetor air filter and/or to the carburetor itself and/or to a fuel body and/or a fuel line.

The adjustability of the deflector concept thus facilitates an overall direction of exhaust fluid so as to maintain optimum safety standards and direct warm air, where desirable, into areas where heatcontent of the exhaust 'gas may be effectively utilized.

THIRD EMBODIMENT INCLUDING VENTED, REED CONTROLLED OUTLET FIGS. 11, 12 and 13 illustrate a particularly unique embodiment of the invention wherein a cantilever beam structure 8 serves to provide augmented, sound reducing action.

This structure synergistically interrelates the vented I reed concept featured in the aforesaid pending application Ser. No. 101,572 with certain principal muffler permit the head of fastener 803 to engage the exterior of plate 801 and press the corner of the plate surrounding opening 805 against the exterior of the surge chamber 4.

As described in connection with fasteners 713, the fastener 803 may threadably engage a threaded female fitment means 715 carried on the inside of chamber 4 adjacent fastener receiving recess 711.

Somewhat similarly, fastener 804 may be provided with a chamfered or frustoconical head 806 which abuttin'gly engages a frustoconical recess or rim 807 adjacent an opening 808 in theplate 801. This abutting cooperation between fastener head 806 and rim 807 will enable the fastener 804 to threadably engage the previously noted female threaded fastener means 714 so as to secure the portion of the plate 801 surrounding opening 807 to the exterior of the surge chamber 4. Head 806, in being chamfered and received in frustoconical recess 807, will be secured so as to be flush with, or recessed below, the outer surface of plate 801.

Mounting plate 801, as shown in FIG. 11, will serve to secure the acoustic filter means 5 in place in the same manner that mounting ring 706 serves to secure this assembly in place, as described in connection with the preceding embodiments.

In this connection, it is'contemplated that in many instances the acoustic filter means 5 may be operated in conjunction with the cantilever beam assembly 8, with the spark arrestor 513 being omitted, as shown in FIG. 11 and FIG. 12.

A flexible flat metallic reed or cantilever beam 809 is superposed outside of the mounting plate 801 as generally shown in FIGS. 11-13 and is secured at one end or extremity 810 against the exterior of the surge chamber. It should here be appreciated that the mounting plate 801 may be considered, in essence, as constituting an exterior portion of the surge chamber 4.

Flexible reed 809 extends generally parallel with the principal vibration plate heretofore described, i.e., generally perpendicular of the axis 502. Reed 809 extends transversely across the passage 510 and has a width sufficient to slightly laterally overlap the lateral edges of the opening 802 as shown generally in FIG. 13. However, the free end 811 ofreed 809 is free to flex outwardly away from opening 510 and plate 801 in response to the pressure of exhaust fluid flowing outwardly of passage 51], outlet means 510, and opening 802. This flexing action provides a significant degree of sound attenuation as described in my prior US. Pat. No. 3,418,412 and my prior pending application Ser. No. 101 ,572, the disclosures of which are herein incorporated by reference.

End810 of reed 809 may lie beneath a generally flat stiffener plate 812. Stiffener plate 812 overlies secured or fastened end 810 of the reed 809 but stops somewhat short of the upper edge of the opening 802, viewing the read as shown in FIG. 11.

Stiffener plate 812 and rim end 810 are secured in place by threaded fasteners 813 and 814. Threaded fastener 813 passes through openings 815 and 816 of stiffenerplate 812 and reed 809, respectively, to intersect a threaded female socket 817 in mounting plate 801. Similarly, threaded fastener 714 passes through openings 818 and 819 of stiffener plate 812 and reed 809, respectively, to be received by a threaded socket 820 of mounting plate 801.

The headed nature of fastening means 813 and 814 enables these fastener means to effectively sandwich together or mutually secure the plate 812, reed end 810, and anchor plate 801 so as to provide an effective anchoring for the reed end 810. The extension of the stiffener plate 812 longitudinally and partially along reed 809 provides a stiffened type of flexing action for the reed so as to prolong operating life of the reed and minimize reed breaking or overdeflection tendencies.

Both the stiffener plate 812 and the reed 809 are preferably fabricated from resilient, spring-like, heat resistant metal. Thus, the plate 812 resiliently impedes flexing of the reed 809 with each of the reeds 809 and plate 812 resiliently flexing in response to fluctuations in exhaust pressure. This stiffening, in addition to prolonging operating life of the reed assembly, also tends to prevent undesired resonant vibration of the reed 809.

The termination of reed end 811 at a location radially inwardly of the opening 802, as shown generally in FIG 11, provides a continuous vent passage or vent means 821. The continuously operable vent, at the lower end of passage means 511, viewing the apparatus as shown in FIG. 11, permits a continuous passage of exhaust fluid through outlet means 510 independent of the position of end 811 of the reed 809, the vent 821 will enable a continuous flow of exhaust fluid out of the outlet means 510.

Advantages of this continuous venting arrangement in conjunction with a cantilever beam reed type sound attenuator are described in detail in my prior application Ser. No. 101,572, as heretofore noted.

SUMMARY OF MAJOR ADVANTAGES AND OVERALL SCOPE OF INVENTION The overall ruggedness of the muffler assembly heretofore described enables the operating life of a muffler to be substantially prolonged.

Where the cylindrical spark arrestor is utilized and disposed inwardly of the supporting cylinder 501, its ruggedized and protected structure minimizes the tendency for the spark arrestor to become broken or destroyed during operation. In the event that some fragmenting of the inner cylinder 503 should occur, fragments may exit readily out of the outlet means 510 so as to prevent their accumulating within the interior of the muffler.

The adjustable deflector assembly provides an operator wtih optimum flexibility with respect to the utilization of exhaust fluid and appropriate orientation of the exhaust flow for safety purposes.

The use of the flexible reed including the vent means in combination with other components of the described muffler mechanism, enables the flexible reed benefits to be enjoyed in association with the benefits of prolonged operating life attributable to basic structural characteristics of this muffler.

The muffler mounting, entailing metal-to-metal contact between the muffler and cylinder minimizes tendencies for the muffler to loosen during operation.

The nature of the deflectors discussed in connection with the invention, including arcuate wall means 701 and arcuate wall means 719, is'such as to provide a diverging exhaust outflow. This outflow may be viewed as being somewhat conical in nature.

This advantageous discharge pattern of exhaust fluid, passing, for example, through area 716, tends to dissipate exhaust energy rapidly so as to reduce fire hazards.

This dispersing exhaust flow also tends to cause a mixing of air with the exhaust fluid so as to rather promptly reduce exhaust temperatures.

The tubular baffle means are believed to contribute to a reduction in airborne noise while concurrently functioning to house and shield fasteners, baffle exhaust flow, and support and secure muffler walls.

The reduction in sound level achieved by the muffler is deemed to be significant and may be attributed in varying degrees to various combinations of structual elements as defined in the appended claims.

Although the precise phenomena is not fully understood, it is believed that some operating advantages of the invention may be attributable to the unique context of utilization of the muffler, i.e., the use of the muffler in association with a chain saw, along with particular configurations and orientations of components as described in the appended claims.

These beliefs notwithstanding, it will be recognized that certain significant aspects of the invention may be derived while accommodating substantial variations in sizing, configuration, orientation and shape of components as well as in the selection of components to be employed in combination.

Since those'skilled in the chain saw muffler art and familiar with this disclosure will doubtless envision such modifications, deletions, substitutions, or other alterations, the overall scope of the invention is deemed to be set forth in the appended claims.

What is claimed is:

1. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain includes:

chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means,

chain saw engine means including piston and cylinder means, and

crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means; said apparatus comprising:

conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, surge chamber means, I

said surge chamber means being operable to receive exhaust fluid from said conduit means,

said surge chamber means being supported on the exterior of said cylinder means,

acoustic filter means including first, generally perforate, outlet passage defining means,

a generally longitudinal axis of said first outlet passage defining means being transversely desplaced from a generally longitudinal axis of of said conduit means, with said conduit means and said first outlet passage defining means being mutually, transversely offset,

second, generally perforate, outlet passage defining means contained within said first outlet passage defining means and at least partially spaced therefrom.

first end portions of each of said first and second outlet passage defining means housed within the interior of said surge chamber means,

barrier means closing said first end portions of said first and second outlet passage'defining means,

perforate wall means extending generally transversely of and between second end portions of said first and second outlet passage defining means,

outlet means provided by a second end of said sec- 0nd outlet passage defining means,

said outlet means and said perforate wall means being operable to transmit exhaust fluid to the exterior of said surge chamber means,

said first outlet passage defining means including a plurality of first perforation means,

said second outlet passage defining means including a plurality of second perforation means, with said second perforation means being operable to arrest the passage of sparks,

each said first perforation means of said first outlet passage defining means generally encircling, and exposing to the interior of said surge chamber means, a plurality of second perforation means of said second outlet passage defining means,

constricted flow path means interposed generally between said first and second outlet passage defining means;

deflector means operable to deflect exhaust fluid exiting from said outlet means of said second outlet passage defining means. 2. An apparatus as described in claim 1 wherein said deflector means comprises:

. arcuate wall means comprising a generally quarter sphere configuration;

means rotatably supporting said arcuate wall means for rotation about a longitudinal axis of said second, outlet passage defining means; and

locking means for selectively securing said arcuate wall means in a selected position of rotation.

3. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain includes:

chain saw cutting means including guide bar means,

cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw;

chain saw engine means including piston and cylinder means, and

crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means,

said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising:

conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means,

said conduit means having a generally rectangularly elongate cross section, and

said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation;

surge chamber means,

said surge chamber means being operable to receive exhaust fluid from said conduit means,

said surge chamber means being supported on the exterior of said cylinder means,

said conduit means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and disposed in direct, metal-to-metal engagement therewith,

said surge chamber means having a generally rectangular configuration including a generally rectangular cross section extending generally parallel with said principal vibration plane;

acoustic filter means including first, generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation,

a longitudinal, generally central axis of said first cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said first cylinder means being mutually, transversely offset,

second, generally perforate cylinder means contained within said first cylinder means and at least partially spaced therefrom.

first end portions of each of said first and second cylinder means which are generally mutually contiguous and housed within the interior of said surge chamber means,

barrier means closing said first end portions of said first and second cylinder means,

perforate wall means extending generally transversely of and between second end portions of said first and second cylinder means,

outlet means provided by a second end of said second cylinder means,

said outlet means and said perforate wall means being operable to transmit exhaust fluid to the exterior of said surge chamber means,

said first cylinder means including a plurality of generally radially opening and circumferentially spaced first perforation means,

said second cylinder means including a plurality of generally radially opening and circumferentially spaced second perforation means, with said second perforation means being operable to arrest the passage of sparks,

each said first perforation means of said first cylin der means generally encircling, and exposing to the interior of said surge chamber means, a plurality of second perforation means of said second cylinder means,

constricted, annular flow path means interposed generally radially between first and second cylinder means and including a generally imperforate portion of said first cylinder means located generally adjacent said perforate wall means,

said constricted, annular flow path means extending along an axis which is generally perpendicular to said principal vibration plane,

said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said first and second cylinder means to generate vibrations therein directed generally transversely of said constricted annular flow path and in general alignment with said principal vibration plane; a plurality of tubular baffle means,

said tubular baffle means being located within the interior of said surge chamber means, each said tubular baffle means extending generally parallel to said axis of crankshaft rotation, and said tubular baffle means being mutually displaced and spaced generally radially outwardly of said first cylinder means; said conduit means, said first and second cylinder means, said constricted annular flow path and said tubular baffle means being generally mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane; and

arcuate deflector means operable to deflect exhaust fluid exiting from said outlet means of said second cylinder means generally transverselyof said axis of crankshaft rotation, said arcuate deflector means including, arcuate wall means comprising a generally quarter sphere configuration,

said generally quarter sphere configuration having a center of curvature generally coincident with a generally central longitudinal axis of said second cylinder means.

4. In a chain saw including an apparatus for reducing the noise generated by an operating chainsaw wherein said chain saw includes:

chain saw cutting means including guide bar means,

cutter chain means supported on said guide bar means for movement through a cutting plane with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw;

chain saw engine meansincluding piston and cylinder means,

crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means,

and

said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising:

conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means,

said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation;

surge chamber means,

said surge chamber means being operable to receive exhaust fluid from said conduit means,

said surge chamber means being supported on the exterior of said cylinder means,

said surge chamber means having a generally rectangular cross section extending parallel with said principal vibration plane;

acoustic filter means including outlet means provided by a second end of said passage cylinder means,

said outlet means being operable to transmit exhaust fluid to the exterior of said surge chamber means,

said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and

said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane,

cantilever beam means extending generally transversely across said outlet means of said outlet passage defining means and including flexible reed means, and

cantilever support, anchor means fixedly securing one end of said reed means to the exterior of said surge chamber means, with another end of said reed means extending at least partially across said outlet means and movable generally outwardly thereof.

5. ln achain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain saw includes:

chain saw cutting means including guide bar means,

cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw;

chain saw engine means including piston and cylinder means, and

crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving forceto said cutter chain means,

said crankshaft means being mounted for rotation said surge chamber means being supported on the exterior of said cylinder means,

said conduit means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and disposed in direct, metal-to-metal engagement therewith,

said surge chamber means having a generally rectangular configuration including a generally rectangular cross section extending generally parallel with said principal vibration plane;

acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation,

a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversely offset,

barrier means within said surge chamber means closing a first end portion of said cylinder means,

outlet means provided by a second end of said cylinder means,

said outlet means being operable to transmit exhaust fluid to the exterior of said chamber means,

said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means,

said cutter chain means and chain saw engine means being operable to generate vibrations generallyaligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane;

a plurality of tubular baffle means,

said tubular baffle means being located within the interior of said surge chamber means,

each said tubular baffle means extending generally parallel to said axis of crankshaft rotation, and

said tubular baffle means being mutually displaced and spaced generally radially outwardly of said cylinder means;

said conduit means, said cylinder means and said tubular baffle means being generally mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane;

and

cantilever beam means extending generally transversely across said outlet means of said cylinder means and including generally flat, flexible reed means extending generally parallel with said principal vibration plane,

cantilever support, anchor means fixedly securing one end of said generally flat reed means to the exterior of said surge chamber means, with another end of said generally flat reed means extending at least partially across said outlet means and movable generally outwardly thereof, and

flexible stiffener means overlapping and generally contiguous with said generally flat reed means and operable to permit, but resiliently impede, flexing of said generally flat reed means in response to the pressure of exhaust fluid passing through said outlet means; and

continuously open vent means permitting a continuous passage of exhaust fluid through said outlet'means independent of the position of said other end of said generally flat reed means relative to said outlet means.

6. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw, wherein said chain saw includes:

chain saw cutting means including guide bar means,

cutter chain means supported on said guide bar means for movement through a cutting plane with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw;

chain saw engine means including piston and cylinder means,

crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means; and I I said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means;

said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation;

surge chamber means,

said surge chamber means being operable to receive exhaust fluid from said conduit means;

said surge chamber means having a generally rectangular cross section extending generally parallel with said principal vibration plane;

acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation,

a longitudinahgenerally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said .conduit means and said cylinder means being mutually, transversely offset,

barrier means within said surge chamber means closing a first end portion of said cylinder means,

outlet means provided by a second end of said cylinder means,

said outlet means being operable to transmit exhaust fluid to the exterior of said surge chamber means,

said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and

said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane. 7. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw, wherein said chain sawincludes:

chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being alignedrin generally parallel relation with a principal vibration plane of a chain saw; chain saw engine means including piston and cylinder means, crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving forceto said cutter chain means,

said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising:

conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, 7

said conduit means having a generally rectangularly elongate cross section, and

said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation;

surge chamber means,

said surge chamber means being operable to receive exhaust fluid from said conduit means,

said surge chamber means being supported on the exterior of said cylinder means,

said conduit means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and dis posed in direct, metal-to-metal engagement therewith,

said surge chamber means having a generally rectangular conflguration including a generally rectangular cross section extending generally parallel with said principal vibration plane;

acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation,

a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversely offset,

barrier means within said surge chamber means closing a first end portion of said cylinder means,

outlet means provided by a second end of said second cylinder means,

said outlet means being operable to transmit exhaust fluid to the exteriorof said surge chamber means,

said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and

said cutter chain means and chain saw engine means being operable to generate vibrations genparallel to said axis of crankshaft rotation, and said tubular baffle means mutually displaced and spaced generally radially outwardly of said cylinder means; said conduit means, said cylinder means, and said tubular baffle means being generally-mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane.

nitrite STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 798, 769 Dated May 7, 1974 Inventor(s) Jay Richard Bailey It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 23 Omit "bracket 30W" after "at" and substitute --a loW--. 7 C01. 4, line 62 After 'in" quotation marks enclosing "exploded format" in typed application are omitted in printed copy.

C01. 5, line 7 l After "muffler" omit "1" and. insert --2--.

C01. 8, line 41 I C After "a" change "from" to e-form".

C01. 12, line 27 I Before "of" (last word) change "hazzard" to '-hazard--.

Col. 12, line 64 1 After "4" omit "is" and insert ,--in.

(301.14, line 23 After "821. change "The" to -This-.

Col. 15, line 62 After "of" omit "of" V Col. 16, line 2 I After "therefrom" omit period and insert 4 comma Col. 17, line 30 After "therefrom" omit period and insert comma C01. 17, line 59 After "between" insert -said--.

Col. 18, vline 65 v After fextending insert -genera11y.

Col. 19, lines 11, 12 After "said" omit "passage".

Col. 24, line 2 After "means" insert -being--.

Signed and sealed this 22nd day of October 1974.

SEAL) Attest:

McCOY GIBSON JR. 7 i c. MARSHALL IDANN AttestingOfficer p v Commissioner of Patents F ORM PO-I 050 (10-69) USCOMM-DC 6O376-F'69 U.S. GOVERNMENT PRINTING OFFICE I9, 0-366-33,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,798,769 Daeed May 7, 1974 Inventor(s) Jay Richard Bailey It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 23 Omit "bracket 3ow' after "at" and substitute --a 1ovv--. C01. 4, line 62 After "in' quotation marks enclosing "exploded format" in typed application are omitted in printed copy.

C01. 5, line 7 After "muffler" omit "1" and. insert --2--.

C01. 8, line 41 A After. "a" change 'from" to -fo r m-.

C01. 12, line 27 A Before "of' (last Word) change "hazzard" to --hazard-.

Col. 12, line 64 After"'4" omit "is" and insert ,-in--.

C01. 14, line 23 After "821. change "The" to -'This--.

C01. 15, line 62 After "of' omit "of" Col. 16, line 2 After "therefrom" omit period and. insert comma Col. 17, line 30 After "therefrom" omit period and insert comma C01. 17, line 59 After "between" insert --said-.

Col. 18, line 65 After 'Yextending" insert -genera11y--.

C01. 19, lines 11, 12 After "said" omit "passage".

C01. 24, line 2 After "rneans' insert -being--.

I Signed and sealed this 22nd day of October 1974.

(SEAL) Attest: v

McCOY 4, GIBSON JR. 1 c. MARSHALL DANN-. Attestlng Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMNPD'C 6O376d=69 a u.s. GOVERNMENT PRINTING OFFICE: 19" o-aes-au. 

1. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means, chain saw engine means including piston and cylinder means, and crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means; said apparatus comprising: conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means, said surge chamber means being supported on the exterior of said cylinder means, acoustic filter means including first, generally perforate, outlet passage defining means, a generally longitudinal axis of said first outlet passage defining means being transversely desplaced from a generally longitudinal axis of of said conduit means, with said conduit means and said first outlet passage defining means being mutually, transversely offset, second, generally perforate, outlet passage defining means contained within said first outlet passage defining means and at least partially spaced therefrom. first end portions of each of said first and second outlet passage defining means housed within the interior of said surge chamber means, barrier means closing said first end portions of said first and second outlet passage defining means, perforate wall means extending generally transversely of and between second end portions of said first and second outlet passage defining means, outlet means provided by a second end of said second outlet passage defining means, said outlet means and said perforate wall means being operable to transmit exhaust fluid to the exterior of said surge chamber means, said first outlet passage defining means including a plurality of first perforation means, said second outlet passage defining means including a plurality of second perforation means, with said second perforation means being operable to arrest the passage of sparks, each said first perforation means of said first outlet passage defining means generally encircling, and exposing to the interior of said surge chamber means, a plurality of second perforation means of said second outlet passage defining means, constricted flow path means interposed generally between said first and second outlet passage defining means; deflector means operable to deflect exhaust fluid exiting from said outlet means of said second outlet passage defining means.
 2. An apparatus as described in claim 1 wherein said deflector means comprises: arcuate wall means comprising a generally quarter sphere configuration; means rotatably supporting said arcuate wall means for rotation about a longitudinal axis of said second, outlet passage defining means; and locking means for selectively securing said arcuate wall means in a selected position of rotation.
 3. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being aligned in generally parallel relation with a principal vibRation plane of a chain saw; chain saw engine means including piston and cylinder means, and crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means, said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising: conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, said conduit means having a generally rectangularly elongate cross section, and said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation; surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means, said surge chamber means being supported on the exterior of said cylinder means, said conduit means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and disposed in direct, metal-to-metal engagement therewith, said surge chamber means having a generally rectangular configuration including a generally rectangular cross section extending generally parallel with said principal vibration plane; acoustic filter means including first, generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation, a longitudinal, generally central axis of said first cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said first cylinder means being mutually, transversely offset, second, generally perforate cylinder means contained within said first cylinder means and at least partially spaced therefrom. first end portions of each of said first and second cylinder means which are generally mutually contiguous and housed within the interior of said surge chamber means, barrier means closing said first end portions of said first and second cylinder means, perforate wall means extending generally transversely of and between second end portions of said first and second cylinder means, outlet means provided by a second end of said second cylinder means, said outlet means and said perforate wall means being operable to transmit exhaust fluid to the exterior of said surge chamber means, said first cylinder means including a plurality of generally radially opening and circumferentially spaced first perforation means, said second cylinder means including a plurality of generally radially opening and circumferentially spaced second perforation means, with said second perforation means being operable to arrest the passage of sparks, each said first perforation means of said first cylinder means generally encircling, and exposing to the interior of said surge chamber means, a plurality of second perforation means of said second cylinder means, constricted, annular flow path means interposed generally radially between first and second cylinder means and including a generally imperforate portion of said first cylinder means located generally adjacent said perforate wall means, said constricted, annular flow path means extending along an axis which is generally perpendicular to said principal vibration plane, said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said first and second cylinder means to generate vibrations therein directed generally transversely of said constricted annular flow path and in general alignment with said principal vibration plane; a plurality of tubular baffle means, said tubular baffle means being located within the interior of said surge chamber means, each said tubular baffle means extending generAlly parallel to said axis of crankshaft rotation, and said tubular baffle means being mutually displaced and spaced generally radially outwardly of said first cylinder means; said conduit means, said first and second cylinder means, said constricted annular flow path and said tubular baffle means being generally mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane; and arcuate deflector means operable to deflect exhaust fluid exiting from said outlet means of said second cylinder means generally transversely of said axis of crankshaft rotation, said arcuate deflector means including, arcuate wall means comprising a generally quarter sphere configuration, said generally quarter sphere configuration having a center of curvature generally coincident with a generally central longitudinal axis of said second cylinder means.
 4. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain saw includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw; chain saw engine means including piston and cylinder means, crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means, and said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising: conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation; surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means, said surge chamber means being supported on the exterior of said cylinder means, said surge chamber means having a generally rectangular cross section extending parallel with said principal vibration plane; acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation, a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversly offset, barrier means within said surge chamber means closing a first end portion of said cylinder means, outlet means provided by a second end of said passage cylinder means, said outlet means being operable to transmit exhaust fluid to the exterior of said surge chamber means, said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane, cantilever beam means extending generally transversely across said outlet means of said outlet passage defining means and including flexible reed means, and cantilever support, anchor means fixedly securing one end of said reed means to the exterior of said surge chamber means, with another end of said reed means extending at least partially across said outlet means and movable generally outwardly thereof.
 5. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw wherein said chain saw includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw; chain saw engine means including piston and cylinder means, and crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means, said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising: conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, said conduit means having a generally rectangularly elongate cross section, and said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation; surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means, said surge chamber means being supported on the exterior of said cylinder means, said conduit means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and disposed in direct, metal-to-metal engagement therewith, said surge chamber means having a generally rectangular configuration including a generally rectangular cross section extending generally parallel with said principal vibration plane; acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation, a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversely offset, barrier means within said surge chamber means closing a first end portion of said cylinder means, outlet means provided by a second end of said cylinder means, said outlet means being operable to transmit exhaust fluid to the exterior of said chamber means, said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane; a plurality of tubular baffle means, said tubular baffle means being located within the interior of said surge chamber means, each said tubular baffle means extending generally parallel to said axis of crankshaft rotation, and said tubular baffle means being mutually displaced and spaced generally radially outwardly of said cylinder means; said conduit means, said cylinder means and said tubular baffle means being generally mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane; and cantilever beam means extending generally transversely across said outlet means of said cylinder means and including generally flat, flexible reed means extending generally parallel with said principal vibration plane, cantilever support, anchor means fixedly securing one end of said generally flat reed means to the exterior of said surge chamber means, with another end of said generally flat reed means extending at least partially across said outlet means and movable generally outwardly thereof, and flexible stiffener means overlapping and generally contiguous with said generally flat reed means and operable to permit, but resiliently impede, flexing of said generally flat reed means in response to the pressure of exhaust fluid passing through said outlEt means; and continuously open vent means permitting a continuous passage of exhaust fluid through said outlet means independent of the position of said other end of said generally flat reed means relative to said outlet means.
 6. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw, wherein said chain saw includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw; chain saw engine means including piston and cylinder means, crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means; and said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means; said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation; surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means; said surge chamber means having a generally rectangular cross section extending generally parallel with said principal vibration plane; acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation, a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversely offset, barrier means within said surge chamber means closing a first end portion of said cylinder means, outlet means provided by a second end of said cylinder means, said outlet means being operable to transmit exhaust fluid to the exterior of said surge chamber means, said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane.
 7. In a chain saw including an apparatus for reducing the noise generated by an operating chain saw, wherein said chain saw includes: chain saw cutting means including guide bar means, cutter chain means supported on said guide bar means for movement through a cutting plane, with said cutting plane being aligned in generally parallel relation with a principal vibration plane of a chain saw; chain saw engine means including piston and cylinder means, crankshaft means driven by said piston means of said piston and cylinder means, and operable to transmit driving force to said cutter chain means, said crankshaft means being mounted for rotation about an axis of crankshaft rotation extending generally perpendicular to said principal vibration plane; said apparatus comprising: conduit means operable to transmit exhaust fluid from said cylinder means of said piston and cylinder means, said conduit means having a generally rectangularly elongate cross section, and said conduit means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation; surge chamber means, said surge chamber means being operable to receive exhaust fluid from said conduit means, said surge chamber means being supported on the exterior of said cylinder means, said conduiT means extending from said surge chamber means and being directly connected with the exterior of said cylinder means and disposed in direct, metal-to-metal engagement therewith, said surge chamber means having a generally rectangular configuration including a generally rectangular cross section extending generally parallel with said principal vibration plane; acoustic filter means including generally perforate cylinder means having a longitudinal axis extending generally parallel to said axis of crankshaft rotation, a longitudinal, generally central axis of said cylinder means being transversely displaced from a longitudinal, generally central axis of said conduit means, with said conduit means and said cylinder means being mutually, transversely offset, barrier means within said surge chamber means closing a first end portion of said cylinder means, outlet means provided by a second end of said second cylinder means, said outlet means being operable to transmit exhaust fluid to the exterior of said surge chamber means, said cylinder means including a plurality of generally radially opening and circumferentially spaced perforation means, and said cutter chain means and chain saw engine means being operable to generate vibrations generally aligned with said principal vibration plane and acting on said cylinder means to generate vibrations therein directed generally transversely thereof and in general alignment with said principal vibration plane; and a plurality of tubular baffle means, said tubular baffle means being located within the interior of said surge chamber means, each said tubular baffle means extending generally parallel to said axis of crankshaft rotation, and said tubular baffle means mutually displaced and spaced generally radially outwardly of said cylinder means; said conduit means, said cylinder means, and said tubular baffle means being generally mutually parallel and subject to said vibrations generated in general alignment with said principal vibration plane. 